Ok, downgraded to Forceware 71.84 and though video playback has not improved (perhaps it was just wishful thinking on my behalf!) the actual stability and benchmark performance seems better.
I get a score of 8500 in 3DMark 2001SE, that's with the following spec:
iBase MB800H (i845GE, s478 up to P4 3.06GHz/533, DDR333, 3xISA, 3xPCI, 1xAGP)
Intel Pentium 4 2.26 (Northwood)
2 x 512MB (no dual channel support)
MSI FX5600 VTDR - testing at 1024x768x32bit
SB16
I'm thinking about fitting a 3.06GHz Northwood (512k l2 cache, 533 fsb, hyperthreading, SSE2, 23x multiplier, 81w tdp) - as that is the best processor that is supported by the MB800H - the only other option is the early 2.80A GHz Prescott (1024k l2 cache, 533 fsb, no-hyperthreading, SSE3, 21x multiplier, 89w tdp).
I've currently got the following cards in the system:
AGP - MSI FX5600 128Mb
PCI - Diamond Monster 3D 4Mb (Voodoo1)
PCI - Netgear 1000BaseT NIC
PCI - (free)
ISA - SB16
ISA - GUS Max
ISA - Midiman MM401
I'm replacing the Netgear NIC with an Intel Pro 1000MT, as the Netgear is flaky under Win98 (though bizarrely, absolutely fine under Linux on the same machine), and will probably add a SB Live to the free PCI slot and remove the SB16 drivers to get better windows sound support (though the SB16 will stay for Dos).
(edit: iBase, not Iwill!)
My collection database and technical wiki:
https://www.target-earth.net